The typical telephone equipment compatible keypad, such as is used on a plain old telephone set (POTS), is an array of twelve manually actuated control elements arranged in four rows of three control elements each. These telephonic type keypads typically code for the numbers 0 through 9 and the symbols “*” and “#”. These keypads do not separately code for alphabetical characters. Although the keypads may be marked with alphabetical characters, for example, the “2” key also corresponds to the letters “A”, “B”, and “C.” Therefore, on the typical telephonic keypad, a single key does not code for a separate alphabetical character (alpha-character).
However, as the use of personal electronic devices and software applications continues to increase, many of these applications require a user to enter alpha-character information to accomplish their full utility. Many personal electronic devices, such as cellular telephones, are limited in the amount of surface area on which to mount a keypad. Therefore, the field has been motivated to provide devices or methods adapting the typical telephonic keypad to additionally code for separate alpha-characters.
In one method of using the typical telephonic keypad to code for alpha-characters, the user presses the key associated with the desired character. Since each key represents several characters, the application must determine which of these characters is intended by the user. This is often accomplished by allowing the user to iterate though the possible characters by pressing the corresponding key multiple times. For example, to enter the number “2” the key “2” is pressed once. However, to enter the letter “C”, the user would press the “2” key three additional times with a time period immediately following pressing the key “2” the first time. To enter the letter “B,” the user would press the “2” key an additional two times.
In another approach, a special key (e.g., the “*” key) is pressed first to shift the keypad into alpha-character mode, and then the numeric key corresponding to the desired alpha-character is repeatedly pressed a number of times corresponding to place in the sequence the desired alpha-character is listed on the numeric key. For example, if the desired alpha-character is “B,” then the “*” key is pressed and the “2” key is pressed twice. See Schneider-Hufschmidt et al., U.S. Pat. No. 6,130,628. In some applications, each time the numeric key is pressed in the alpha-character mode, the corresponding letter may be presented to the user (e.g., via data display). Burrell, U.S. Pat. No. 6,043,761, discloses an approach similar to Schneider-Hufschmidt et al. for using a twelve button numeric keypad to generate alpha-characters.
Typically in these approaches, after the keypad is in alpha mode, the iteration through characters starts with the first character of the series for that numeric key. For example, when using the “2” key in alpha mode, iteration starts at “A.” Accordingly, for at least two-thirds of the characters entered on the keypad, multiple key presses are required. Knowlton, U.S. Pat. No. 3,967,273, early on described a method that can be adapted to require only two button pushes on twelve button telephonic keypad to select an input from a large set of alphanumeric characters. However, the Knowlton device does not teach a typically telephonic configured keypad labeling system, and required at least two button pushes to enter an alpha-character. Still, using any of these techniques to enter entire words and sentences is tedious and error-prone, and results in a user's limited use of applications requiring text entry on devices using numeric keypads (e.g., telephones). It is also slow and typically requires frequent checks of the visual display, if available, to assure accuracy. Also, PDA's can have a keypad and a (LCD) keyboard, which requires a stylus or a mouse to enter alpha characters.
In an example of a prior technology alphanumeric coding for the letter sequence “abc,” once in the alpha-character mode, the “2” button is pressed three times, the # button once, the “2” button is pressed once, the # button once and then the “2” button is pressed twice, for a total of 8 actions. It is an object of the present keypad, that once a character set is selected via a mode or shift key, only three press operations are required to code for the same sequence of letters. Entering spaces required pressing the # button twice on some prior keypads. An advantage of the present invention is that a space may be entered in a single press.
In view of these limitations, it would be beneficial to have a telephonic type keypad that required only a single stroke to code for alpha-characters (including symbols), and did not require the use of an ancillary tool to make inputs.